Christensen M J, Burgener K W
Department of Food Science and Nutrition, Brigham Young University, Provo, UT 84602.
J Nutr. 1992 Aug;122(8):1620-6. doi: 10.1093/jn/122.8.1620.
The objective of these studies was to determine the step at which dietary selenium (Se) regulates the pre-translational expression of the gene for cytosolic Se-glutathione peroxidase (Se-GPX) in rat liver. Weanling male Sprague-Dawley rats were fed a Torula yeast-based Se-deficient diet, or the same diet supplemented with 0.5 mg/kg as Na2SeO3, for at least 40 d. Livers were excised and divided into three portions for isolation of nuclei, for purification of total RNA and for assay of Se-GPX activity. Nuclei were used in run-on transcription assays and for isolation of total nuclear RNA. Nuclear RNA and total liver RNA were probed with segments from a rat Se-GPX cDNA in Northern blot and slot blot assays. Despite marked differences in Se-GPX activity, there were no significant differences between dietary groups in the transcription rates of the Se-GPX gene. Species hybridizing to Se-GPX were not detected in nuclear RNA. However, steady state levels of Se-GPX mRNA were markedly reduced by Se deficiency. These results suggest that dietary Se exerts its effect on pretranslational Se-GPX gene expression at the level of cytosolic mRNA stabilization.
这些研究的目的是确定膳食硒（Se）在大鼠肝脏中调节胞质硒谷胱甘肽过氧化物酶（Se-GPX）基因转录前表达的步骤。将断乳雄性Sprague-Dawley大鼠喂食以产朊假丝酵母为基础的缺硒饲料，或添加0.5 mg/kg亚硒酸钠的相同饲料，持续至少40天。切除肝脏并分成三份，分别用于分离细胞核、纯化总RNA和测定Se-GPX活性。细胞核用于进行连续转录分析和分离总核RNA。在Northern印迹和狭缝印迹分析中，用大鼠Se-GPX cDNA片段探测核RNA和肝脏总RNA。尽管Se-GPX活性存在显著差异，但不同饮食组之间Se-GPX基因的转录速率没有显著差异。在核RNA中未检测到与Se-GPX杂交的物种。然而，缺硒显著降低了Se-GPX mRNA的稳态水平。这些结果表明，膳食硒在胞质mRNA稳定水平上对转录前Se-GPX基因表达发挥作用。
